In recent years, a client/server system becomes widespread, in which a client terminal and a server apparatus are communicably connected through a network. An information processing service is provided to a user of the client terminal by executing predetermined information processing by the server apparatus in response to a request transmitted from the client terminal.
Also, as described in Japanese Patent Publications (JP 2007-226719A, JP-A-Heisei 9-198357, JP 2006-107185A and JP-A-Heisei 9-016534), techniques are also developed in which the information processing of an application that is being executed by the server apparatus is shifted to the client terminal and executed there, in response to operation environment of the client terminal or the server apparatus.
In the above Japanese Patent Publication (JP 2007-226719A), even if the operation environment is changed, the application is efficiently executed. A server determines configuration information on a first platform, and a client downloads client configuration information from the server. The server and the client assemble the configuration on the basis of server configuration information and the client configuration information, respectively. Also, each of the server and the client determines whether or not re-balance processing should be started by a re-balance controller which periodically calls a re-balance adviser. In this way, the dynamic re-configuration (re-balance) that involves movement or exchange in units of functions of the configuration is carried out in accordance with current operation environment.
Also, in the above Japanese Patent Publication (JP-A-Heisei 9-198357), in a client/server system, a load due to the start of an application program is effectively distributed. In the client/server system, the server obtains its own CPU load information and controls the start of the application program possessed by itself. When a value of the CPU load information of the server is equal to or greater than a threshold of the load, the client requires the start of the application program in the client, and in a case of being less than the threshold of the load, the client requires the start of the application program in the server. Also, the client controls the start of each application program in response to a start request.
Moreover, in the above Japanese Patent Publication (JP 2006-107185A), in a server-based computation environment, even in a place in which network connection is impossible, the same environment as environment attained by the server is safely provided to a user on a terminal. A virtual computer is configured on the server, and the application program is executed on the virtual computer by the client. When the client is disconnected, data required to configure the virtual computer is converted into a file and transferred to the client in its original state. The processing is continued on the client by the virtual computer configured from the received file.
On the other hand, in Japanese Patent Publication (JP-A-Heisei 9-016534), in the environment of computers that are coupled through a network and uniformly or non-uniformly distributed, a job from a user is efficiently distributed and executed on the server. For a process flow of an application program for the job from the user, an agent process is generated between a client process and a server process. The job requested by the client process is distributed to the server processes by the agent process and executed therein on the basis of information of hardware resources such as a static performance of a computer and a dynamic change of load situation, and information of software resources such as data associated with a program module in the computer environment.
Here, when the processing of an application program being executed by the server apparatus is shifted to the client terminal, a communication has to be carried out in order to check the operation situation between the client terminal and the server apparatus. For this reason, in a conventional technique, it is difficult to shift the information processing when the communication became impossible between the client terminal and the server apparatus.
In the technique described in the Japanese Patent Publication (JP 2007-226719A), when the module is re-configured on the basis of change in environment, communications are carried out to notify environment information from the client to the server or to download the module into the client. The technique cannot deal with a situation in which the network is disconnected. In particular, such a situation cannot be determined on the basis of only the environment information of the server, and it is necessary to determine only on the client side. Also, transmission to and reception from the server are impossible, and countermeasure software cannot be received from the server.
Also, in the technique described in the Japanese Patent Publication (JP-A-Heisei 9-198357), since communication is required to acquire the CPU load information of the server, the technique cannot deal with the situation in which the network is disconnected.
Also, the Japanese Patent Publication (JP 2006-107185A) discloses that when the user disconnects a client from the server, personal environment information at that time is duplicated on the client as it is. However, any duplication of the personal environment information for unpredicted disconnection such as disconnection when a Shinkansen train passes through a tunnel is not described at all.
Moreover, the Japanese Patent Publication (JP-A-Heisei 9-016534) discloses that both of the client and the server have processes, and the processes are generated or deleted on the basis of the load situation. However, even in this case, when the communication becomes impossible between the client terminal and the server apparatus, it is difficult to shift the information processing.